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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 ...
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 ]
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 ...