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Lipofectamine or Lipofectamine 2000 is a common transfection reagent, produced and sold by Invitrogen, used in molecular and cellular biology. [1] It is used to increase the transfection efficiency of RNA (including mRNA and siRNA ) or plasmid DNA into in vitro cell cultures by lipofection . [ 1 ]
A difference engine is an automatic mechanical calculator designed to tabulate polynomial functions. It was designed in the 1820s, and was first created by Charles Babbage . The name difference engine is derived from the method of finite differences , a way to interpolate or tabulate functions by using a small set of polynomial co-efficients.
In mathematics, divided differences is an algorithm, historically used for computing tables of logarithms and trigonometric functions. [citation needed] Charles Babbage's difference engine, an early mechanical calculator, was designed to use this algorithm in its operation. [1] Divided differences is a recursive division process.
[2] [3] It was first described in 1837 as the successor to Babbage's Difference Engine, which was a design for a simpler mechanical calculator. [ 4 ] The analytical engine incorporated an arithmetic logic unit , control flow in the form of conditional branching and loops , and integrated memory , making it the first design for a general-purpose ...
Casio V.P.A.M. calculators are scientific calculators made by Casio which use Casio's Visually Perfect Algebraic Method (V.P.A.M.), Natural Display or Natural V.P.A.M. input methods. V.P.A.M. is an infix system for entering mathematical expressions, used by Casio in most of its current scientific calculators.
On a single-step or immediate-execution calculator, the user presses a key for each operation, calculating all the intermediate results, before the final value is shown. [1] [2] [3] On an expression or formula calculator, one types in an expression and then presses a key, such as "=" or "Enter", to evaluate the expression.
The calculator is powered by two CR2032 button cells connected in parallel, which it is advised to replace one at a time, to avoid memory loss. [ 7 ] It was initially supplied with a hard zippered clamshell case with a pocket for notes, and a printed manual, [ 10 ] but this was later changed to a slipcase made of vinyl-covered cardboard with ...
Difference in differences (DID [1] or DD [2]) is a statistical technique used in econometrics and quantitative research in the social sciences that attempts to mimic an experimental research design using observational study data, by studying the differential effect of a treatment on a 'treatment group' versus a 'control group' in a natural experiment. [3]