Proper velocity by Hermann Minkowski's flat-space metric equation . Here a reference map frame of yardsticks and synchronized clocks define map position x and map time "t" respectively, and the "d" preceding a coordinate means infinitesimal change. A bit of manipulation allows one to show that proper velocity where as usual coordinate velocity . Thus finite "w" ensures that "v" is less than lightspeed "c". By grouping "γ" with v in the expression for relativistic momentum p, proper velocity also extends the Newtonian form of momentum as mass times velocity to high speeds without a need for relativistic mass. The proper velocity
Enzyme multiplied immunoassay technique is a branch of the U.S. Department of Health and Human Services). The setting of reasonable cutoff limits help reduce false positive results that occur from assay limitations. Because of the social and legal consequences, a positive test result must be confirmed by an alternative method, usually Gas Chromatography/Mass spectrometry. As an example the SAMHSA cutoffs for cannabinoids are 50 ng/ml for the immunoassay and 15 ng/ml as confirmed by GC/MS. Immunoassays that do not conform with SAMHSA, featuring a cutoff of 20 ng/ml, have been shown to produce false positives from passive inhalation of marijuana smoke. Enzyme multiplied immunoassay