to distribute, and to distribute heroin, in violation of 21 U.S.C. § 846, and three counts of possession with intent to distribute heroin, in violation of 21 U.S.C. § 841(a)(1). We have jurisdiction pursuant to 28 U.S.C. § 1291, and we affirm. Serrano contends that the district court’s imposition of a 57-month sentence was unreasonable under United States v. Booker, 543 U.S. 220, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005). A sentence is reasonable when the dist d.2d 832 (2006); see also United States v. Mix, 450 F.3d 375, 381 (9th Cir.2006) (amended) (“A district court is not required to refer to each factor listed in § 3553(a).”). Serrano makes three further contentions, all of which are foreclosed by our previous decisions. See United States v. Dupas, 419 F.3d 916, 919-924 (9th Cir. 2005) (<HOLDING>), cert. denied, — U.S. —, 126 S.Ct. 1484, 164
holding retroactive application of idra would violate the ex post facto clause holding that retroactive application of postbooker remedial scheme does not violate ex post facto principles and that delegating authority to probation officer to assess drug treatment costs is not plain error holding that revocation of medical license does not violate the ex post facto clause holding that retroactive application of mvra does not violate the ex post facto clause because restitution is not a criminal punishment holding that district court did not violate ex post facto clause in applying remedial holding of booker at sentencing