|Cyclical neutropenia is also known as cyclic neutropenia, a form of neutropenia which is a granulocyte disorder characterized by an abnormally low number of neutrophils. This tends to occur for every three weeks and lasts from three to six days due to changing rates of cell production by the bone marrow. High-impact journals are those considered to be highly influential in their respective fields. The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.