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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.
A pinwheel calculator is a class of mechanical calculator described as early as 1685, and popular in the 19th and 20th century, calculating via wheels whose number of teeth were adjustable. These wheels, also called pinwheels, could be set by using a side lever which could expose anywhere from 0 to 9 teeth, and therefore when coupled to a ...
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.
Friden made a calculator that also provided square roots, basically by doing division, but with added mechanism that automatically incremented the number in the keyboard in a systematic fashion. The last of the mechanical calculators were likely to have short-cut multiplication, and some ten-key, serial-entry types had decimal-point keys.
[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 ...
Made in Japan, this was also the first calculator to use an LED display, the first hand-held calculator to use a single integrated circuit (then proclaimed as a "calculator on a chip"), the Mostek MK6010, and the first electronic calculator to run off replaceable batteries. Using four AA-size cells the LE-120A measures 4.9 by 2.8 by 0.9 inches ...
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.