Physical properties of prestellar (red) and protostellar (blue) sources at the tips of the bar in the first quadrant (top) and fourth quadrant (bottom). The data in the small windows show the same distributions in the entire fields of view, therefore not only at the bar but also in background and foreground regions. The dashed vertical line at the very left hand side in the size distribution marks the separation between core and clumps according to Bergin & Tafalla (2007).