A process for preparing acrylic acid by heterogeneously catalyzed gas phase partial oxidation of a saturated hydrocarbon precursor compound, in which the charging gas mixture contains from 5 to 25% by volume of steam and the molar ratio of molecular oxygen present in the charging gas mixture to saturated hydrocarbon precursor compound present in the charging gas mixture is from 1. The printing device includes at least one sensor for detecting when a media jam occurs in the media path. The first and second substrates are facing each other. The method further includes the steps of synchronizing the object and object state between the server application and the client application, and updating the object by invoking a server application method after the step of synchronizing. The method for reproducing signals magnetically recorded medium having, on either side of a flexible nonmagnetic support, a nonmagnetic layer containing a nonmagnetic powder and a binder, and a magnetic layer, with a thickness ranging from 0. The apparatus to generate a halftoning screen includes a dot center setting unit to set locations of dot centers according to a plurality of grey levels of print data, and a screen generating unit to grow dots from the locations of the dot centers that are set for each of the plurality of grey levels of the print data.