Best Practices Guide: Fundamentals

OSHA Best Practices Guide Fundamentals of a Workplace First-Aid Program, https //www.osha.gov/Publications/OSFlA3317first-aid.pdf... 

The parallels with Ohm s law also provide a clue about how the choice between diffusion models is made. The mass transfer coefficient in Eq. 1.1-2 and the resistance in Eq. 1.1-4 are simpler, best used for practical situations and rough measurements. The diffusion coefficient in Eq. 1.1-3 and the resistivity in Eq. 1.1-5 are more fundamental, involving physical properties like those found in handbooks. How these differences guide the choice between the two models is the subject of the next section. 

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