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The cover image shows a glassy polymer disc with a pre-made crack across its center; the disc is loaded so as to create in-plane shear stress at the tips of the crack. When the sample fails, the cracks don't grow in the direction of the pre-made crack. Instead, they initiate in the direction corresponding to the maximum opening stress. As the cracks propagate they change direction to minimize the amount of shear stress at the crack tips. Using systematic studies on shear band formation, Jared Archer and Alan Lesser show that fracture through a shear mechanism is possible in glassy polymers, and are able to relate the behavior to the intrinsic material properties of the polymer. Read the full story on page 103 of this issue.