The invention provides methods and compositions for assaying hypoxia-inducible factor prolyl hydroxylation. Battery powered devices such cell phones and laptop computers create some noise in the form of negative excursions from the average output voltage of the battery which can cause the battery powered device to stop functioning. We also disclose a container comprising a container structure and a shrink label in contact with the container structure’s exterior surface. If the size of sheets to be post-processed is unsuitable for the post-processing, a flapper is changed over so that the sheets transported from the printer main body are discharged directly to the face-down discharge portion and stacked thereon.