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The notion of doubling time dates to interest on loans in Babylonian mathematics. Clay tablets from circa 2000 BCE include the exercise "Given an interest rate of 1/60 per month (no compounding), come the doubling time." This yields an annual interest rate of 12/60 = 20%, and hence a doubling time of 100% growth/20% growth per year = 5 years.
The Gompertz curve or Gompertz function is a type of mathematical model for a time series, named after Benjamin Gompertz (1779–1865). It is a sigmoid function which describes growth as being slowest at the start and end of a given time period.
Half-life (symbol t ½) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive.
Early on it was found that X-rays, gamma rays, and beta radiation were essentially equivalent for all cell types. Therefore, the standard radiation type X is generally an X-ray beam with 250 keV photons or cobalt-60 gamma rays. As a result, the relative biological effectiveness of beta and photon radiation is essentially 1.
Although scientific calculators and spreadsheet programs have functions to find the accurate doubling time, the rules are useful for mental calculations and when only a basic calculator is available. [2] These rules apply to exponential growth and are therefore used for compound interest as opposed to simple interest calculations.
The LNCaP (Lymph Node Carcinoma of the Prostate) cell line was established from a metastatic lesion of human prostatic adenocarcinoma.The LNCaP cells grow readily in vitro (up to 8 x 10 5 cells/sq cm; doubling time, 60 hr), form clones and are highly resistant to human fibroblast interferon. [1]
If the turbidity, or optical density, of the batch cultures within the 96-well plate is monitored in real time, and the amount of time required for a well to reach a threshold is recorded, and the doubling time of the exponentially growing cells is known, then the number of cells originally present in the inoculum can be calculated.
The doubling time is about 36–48 hours. The cell line was derived from a 36-year-old woman who was originally reported to have acute promyelocytic leukemia at the MD Anderson Cancer Center. [1] HL-60 cells predominantly show neutrophilic promyelocytic morphology. [1]