Are two phases of quarantine better than one?

New research into this question shows that the second wave of an epidemic is very different if a population has a homogenous distribution of contacts, compared to the scenario of subpopulations with diverse number of contacts.

Experimental evolution reveals how bacteria gain drug resistance

A research team at the RIKEN Center for Biosystems Dynamics Research (BDR) in Japan has succeeded in experimentally evolving the common bacteria Escherichia coli under pressure from a large number of individual antibiotics. ...

DNA molecules yield biochemical random number

ETH scientists have generated a huge true random number using DNA synthesis. It is the first time that a number of this magnitude has been created by biochemical means.

Modelling micro-swimmers for drug delivery

Mathematical models of the motion of cells in viscous liquids that show how this motion is affected by the presence of a surfactant coating have applications in the design of artificial micro-swimmers for targeted drug delivery, ...

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Number

A number is a mathematical object used to count and measure. In mathematics, the definition of number has been extended over the years to include such numbers as zero, negative numbers, rational numbers, irrational numbers, and complex numbers.

Mathematical operations are certain procedures that take one or more numbers as input and produce a number as output. Unary operations take a single input number and produce a single output number. For example, the successor operation adds one to an integer, thus the successor of 4 is 5. Binary operations take two input numbers and produce a single output number. Examples of binary operations include addition, subtraction, multiplication, division, and exponentiation. The study of numerical operations is called arithmetic.

A notational symbol that represents a number is called a numeral. In addition to their use in counting and measuring, numerals are often used for labels (telephone numbers), for ordering (serial numbers), and for codes (e.g., ISBNs).

In common use, the word number can mean the abstract object, the symbol, or the word for the number.

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