What is the test for a prison official to be held liable under the Eighth Amendment for failing to protect the health and safety of an inmate?

deprivation alleged must be, objectively, sufficiently serious; a prison official's act or omission must result in the denial of the minimal civilized measure of life's necessities." Id. at 834 (internal quotation marks and citations omitted). Second, the prison official must subjectively have a "sufficiently culpable state of mind," "one of deliberate indifference to inmate health or safety." Id. (internal quotation marks and citations omitted). The official is not liable under the Eighth Amendment unless he "knows of and disregards an excessive risk to inmate health or safety; the official must both be aware of facts from which the inference could be drawn that a substantial risk of serious harm exists, and he must also draw the inference." Id. at 837. Then he must fail to take reasonable measures to abate the substantial risk of serious harm. Id. at 847. A person can deprive another of a constitutional right, within the meaning of 1983, "not only by some kind of direct personal participation in the deprivation, but also by setting in motion a series of acts by others which the actor knows or reasonably should know would cause others to inflict the constitutional injury." Johnson v. Duffy, 588 F.2d 740, 743-44 (9th Cir. 1978).