New atlas of bird migration shows extraordinary journeys

A bay-breasted warbler weighs about the same as four pennies, but twice a year makes an extraordinary journey. The tiny songbird flies nearly 4,000 miles (6,437 kilometers) between Canada's spruce forests and its wintering ...

Quantum light source advances bio-imaging clarity

Texas A&M University researchers accomplished what was once considered impossible—they created a device capable of squeezing the quantum fluctuations of light down to a directed path and used it to enhance contrast imaging.

Optimizing competing instrument needs with an objective metric

Designing instruments for spacecraft missions is an exercise in managing trade-offs. With severe restrictions on power, mass, and volume, space-based instruments are often compromised in ways an equivalent laboratory instrument ...

Noise

In common use, the word noise means any unwanted sound. In both analog and digital electronics, noise is random unwanted perturbation to a wanted signal; it is called noise as a generalisation of the acoustic noise ("static") heard when listening to a weak radio transmission with significant electrical noise. Signal noise is heard as acoustic noise if the signal is converted into sound (e.g., played through a loudspeaker); it manifests as "snow" on a television or video image. High noise levels can block, distort, change or interfere with the meaning of a message in human, animal and electronic communication.

In signal processing or computing it can be considered random unwanted data without meaning; that is, data that is not being used to transmit a signal, but is simply produced as an unwanted by-product of other activities. "Signal-to-noise ratio" is sometimes used to refer to the ratio of useful to irrelevant information in an exchange.

In biology, noise can describe the variability of a measurement around the mean, for example transcriptional noise describes the variability in gene activity between cells in a population.

In many cases, the special case of thermal noise arises, which sets a fundamental lower limit to what can be measured or signaled and is related to basic physical processes described by thermodynamics, some of which are expressible by simple formulae.

In some fields, noise means unwanted information or data that is not relevant to the hypothesis or theory being investigated or tested.

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