About half of those who have mononucleosis have enlargement of the spleen, usually 2 to 3 weeks after they are infected. The incubation periodâthe time it takes symptoms to appear after a person becomes infected with the virusâcan be 4 to 6 weeks.Symptoms of mononucleosis usually last for 1 to 4 weeks, but it might take as long as 2 months before you feel well enough to resume all of your normal activities.bout half of those who have mononucleosis have enlargement of the spleen, usually 2 to 3 weeks after they are infected. The incubation periodâthe time it takes symptoms to appear after a person becomes infected with the virusâcan be 4 to 6 weeks.
hair analysis. chemical analysis of a hair sample to find possible evidence of exposure to a toxic substance. Molecules of lead compounds and other chemicals are absorbed and stored in hair shafts. Hair analysis is also used to determine possible causes of malnutrition.
What is a meta-analysis? Meta-analysis is the statistical procedure for combining data from multiple studies. When the treatment effect (or effect size) is consistent from one study to the next, meta-analysis can be used to identify this common effect. When the effect varies from one study to the next, meta-analysis may be used to identify the reason for the variation. Why perform a meta-analysis? Decisions about the utility of an intervention or the validity of a hypothesis cannot be based on the results of a single study, because results typically vary from one study to the next.