725, 739 (12) (234 SE2d 541) (1977)) that the evidence as to his sexual attack upon a fellow prisoner was insufficient to convict, and that the verdict was against the weight of the evidence. In support of these contentions Heard claims that there were conflicts in the evidence, and attacks the credibility of the state's witnesses.

We affirm. "The jury is the final arbiter of conflicts in the evidence" ( Allen v. State, 145 Ga. App. 426 (243 SE 2d 626) (1978)), and "the appellate courts undertake only to determine the sufficiency of the evidence, not to weigh it." Ridley v. State, 236 Ga. 147, 149 (1) (223 SE2d 131) (1976). We find that a rational trier of fact could reasonably have found from the evidence adduced at trial proof of appellant's guilt beyond a reasonable doubt. Fisher v. State, 151 Ga. App. 93 (258 SE2d 920) (1979).