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Bromochlorodifluoromethane (BCF), also referred to by the code numbers Halon 1211 and Freon 12B1, is a haloalkane with the chemical formula C F 2 Cl Br. It is used for fire suppression, especially for expensive equipment or items that could be damaged by the residue from other types of extinguishers. [ 1 ]
Chlorofluorocarbons ( CFCs) and hydrochlorofluorocarbons ( HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propane . The most common example is dichlorodifluoromethane (R-12). R-12 is also commonly called Freon ...
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Life expectancy, more technically called the curtate expected lifetime and denoted ,[ a] is the mean of —that is to say, the expected number of whole years of life remaining, assuming survival to age . [ 149] So, (2) Substituting ( 1) into the sum and simplifying gives the final result [ 150]
As used in birth control studies, a decrement table calculates a separate effectiveness rate for each month of the study, as well as for a standard period of time (usually 12 months). Use of life table methods eliminates time-related biases (i.e. the most fertile couples getting pregnant and dropping out of the study early, and couples becoming ...
A 2023 map of countries by fertility rate. Blue indicates negative fertility rates. Red indicates positive rates. The total fertility rate (TFR) of a population is the average number of children that are born to a woman over her lifetime, if they were to experience the exact current age-specific fertility rates (ASFRs) through their lifetime, and they were to live from birth until the end of ...
A mother with her child. In the United States, 80% of single parents are mothers. Among this percentage of single mothers: 45% of single mothers are currently divorced or separated, 1.7% are widowed, 34% of single mothers never have been married. [13] This is in contrast to earlier decades, where having a child outside of marriage and/or being ...
This is especially true for Healthy life expectancy, the definition of which criteria may change over time, even within a country. For example, Canada is a country with a fairly high overall life expectancy at 81.63 years; however, this number decreases to 75.5 years for Indigenous people in the country. [ 4 ]