R-factor

R-factor is a term used in various scientific fields, each with a different meaning. In the context of microbiology, it refers to a plasmid that carries antibiotic resistance genes. In crystallography, it is a measure of the quality of a crystal structure solution. In building insulation, it is a measure of thermal resistance.

Microbiology

In microbiology, an R-factor is a type of plasmid that carries antibiotic resistance genes. These plasmids can be transferred between bacteria through a process called bacterial conjugation, which allows for the rapid spread of antibiotic resistance.

R-factors were first discovered in Japan in the 1950s, when researchers noticed that some strains of Escherichia coli were resistant to multiple antibiotics. Further investigation revealed that these bacteria contained plasmids that carried resistance genes for several different antibiotics. These plasmids were named R-factors, with the "R" standing for "resistance".

Crystallography

In crystallography, the R-factor is a measure of the quality of a crystal structure solution. It is calculated as the ratio of the sum of the absolute differences between observed and calculated structure factors to the sum of the observed structure factors. A lower R-factor indicates a better fit between the observed data and the model.

The R-factor is one of several statistics used to assess the quality of a crystal structure solution. Others include the free R-factor, the root-mean-square deviation (RMSD), and the B-factor.

Building Insulation

In the context of building insulation, the R-factor is a measure of thermal resistance. It is used to quantify the ability of a material to resist heat flow. The higher the R-factor, the better the material is at insulating.

The R-factor is determined by the material's thickness and its thermal conductivity. It is typically used in North America, while the U-value is used in most other parts of the world.

See also

• Antibiotic resistance
• Plasmid
• Bacterial conjugation
• Crystallography
• Building insulation

R-factor Resources
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